it immediately prevents it from being used as something like a reddit thread ?

Yes, that's crucial to the definition. I made this because I want a medium that doesn't have deeply nested conversations to enforce participants to stay on topic and contribute to a single "discussion". This has implications for the user interfaces that can be built, and for how people interact on a given topic. This is really the only differentiating factor from kind 1. See flotilla's threads feature for how this looks in practice.